Voltage doubling circuit for laundry treating appliance with high power variable frequency drive

ABSTRACT

A circuit that increases input voltage to higher output voltage connected to a variable frequency drive in an appliance. Several switching arrangements, timing, and safety mechanisms are in place to assist. When the circuit experiences high draw, high voltage output values of circuit decrease over time, but different aspects of the circuit can be constructed so that the amount of time required at a higher voltage does not exceed the amount of time in which the high voltage output is provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/510,026, filed May 23, 2017, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

Laundry treating appliances, such as dryers, clothes washers or washingmachines that have a variable frequency drive (VFD), are rated forservice with certain electrical power supplies. In certain areas of theworld, such as North America, 120 Volts alternating current (VAC)electrical power supplies are prevalent. Smaller appliances with smallerload capacity have a 120 VAC service rating and can operate well using a120 VAC electrical system, but larger appliances with larger loadcapacity, such as certain commercial washing machines, require a highervoltage supply, such as 240 VAC, to operate properly.

There is little to no availability for 120 VAC input and 240 VAC outputcircuitry that can drive VFDs at a high power level (such as greaterthan 750 Watts). Some existing solutions to this problem of insufficientoperating power include using a 120 VAC input variable frequency drive(VFD) and an internal doubling circuit to get a 240 VAC output, but suchmachines are limited to about 4.2 amps of current, not enough to drivesome desired loads in a washing machine. Another solution is to use avery large, heavy, and expensive “step-up” voltage doubling transformerto change from a 120 VAC input to a 240 VAC output.

SUMMARY OF THE INVENTION

In one aspect of the disclosure, a home appliance can be configured toperform a cycle of operation that includes a motor and a voltagedoubling circuit. The voltage doubling circuit includes a power inputthat receives a voltage supply from a power source. The power input isconnected to at least one capacitor bank with a current-limiting surgesuppressor positioned between the power input and the at least onecapacitor bank. The voltage doubling circuit connects to a variablefrequency drive that can cause the motor to operate when supplied with avoltage greater than the voltage supply from the power source.

Another aspect of the present disclosure relates to a method ofoperating a voltage doubling circuit for a laundry treating appliancethat is configured to perform a cycle of operation. The method caninclude the voltage doubling circuit receiving a voltage supply from apower source. A current limiting surge suppressor can define acurrent-limiting path from the voltage supply to at least one capacitorbank to charge the at least one capacitor bank. Once the at least onecapacitor bank is charged to approximately seventy percent of a peakvoltage, charging the at least one capacitor bank can continue through abypass path configured to bypass the current-liming surge suppressor.The at least one capacitor bank can then be at least partiallydischarged to supply a voltage greater than the voltage supply to avariable frequency drive to cause a motor to operate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a laundry treating appliance in the formof a washing machine according to an aspect of the present disclosure.

FIG. 2 is a schematic of a control system of the laundry treatingappliance of FIG. 1.

FIG. 3 is a schematic diagram of a voltage doubling circuit in thecontrol system of FIG. 2.

FIG. 4 is a schematic flow chart showing operation of the voltagedoubling circuit of FIG. 3.

FIG. 5 is a graph that demonstrates voltage verses times of aspects ofthe voltage doubling circuit in FIG. 3.

DESCRIPTION

Systems, components, and methodologies in accordance with the presentdisclosure provide a laundry treating appliance with a variablefrequency drive (VFD) and a control circuit which doubles the inputvoltage so that the laundry treating appliance can have a 120 VACservice rating and supply 240 VDC or more to the VFD, perhaps as much as340 VDC. While 120 VAC is described herein, aspects of the disclosurecan be equally applied to any relevant power distribution system, basedon geography, power supply limitations, or the like. Thus, aspects ofthe disclosure can include increasing a voltage to a VFD, as desired.

The control circuit and related systems, components, and methodologiesare described herein in relation to a laundry treating appliance in theform of a washing machine or dryer, in the same manner, for treatingfabric articles according to a cycle of operation. The washing machinecan be a household or commercial appliance. It should be appreciated,however, that the control circuit and related systems, components, andmethodologies as described herein are not so limited and can have equalapplicability to additional appliances, non-limiting examples of whichinclude a horizontal or vertical axis clothes washer; a dryer; acombination washing machine and dryer; a tumbling or stationaryrefreshing/revitalizing machine; an extractor; a non-aqueous washingapparatus; and a revitalizing machine.

All directional references (e.g., radial, axial, proximal, distal,upper, lower, upward, downward, left, right, lateral, front, back, top,bottom, above, below, vertical, horizontal, clockwise, counterclockwise,upstream, downstream, forward, aft, etc.) are only used foridentification purposes to aid the reader's understanding of the presentdisclosure, and do not create limitations, particularly as to theposition, orientation, or use of aspects of the disclosure describedherein. Connection references (e.g., attached, coupled, connected, andjoined) are to be construed broadly and can include intermediate membersbetween a collection of elements and relative movement between elementsunless otherwise indicated. As such, connection references do notnecessarily infer that two elements are directly connected and in fixedrelation to one another. The exemplary drawings are for purposes ofillustration only and the dimensions, positions, order and relativesizes reflected in the drawings attached hereto can vary.

FIG. 1 is a schematic view of a laundry treating appliance according toone aspect of the present disclosure. The laundry treating appliance ofFIG. 1 is illustrated as a washing machine 10, which can include astructural support system comprising a chassis or cabinet 12 whichdefines a housing within which a laundry holding system resides. Thecabinet 12 can be a housing having a chassis or a frame, defining aninterior enclosing components typically found in a conventional washingmachine, such as motors, pumps, fluid lines, controls, sensors,transducers, and the like. Such components will not be described furtherherein except as necessary for a complete understanding of thedisclosure.

The laundry holding system comprises a tub 14 supported within thecabinet 12 by a suitable suspension system and a drum 16 provided withinthe tub 14, the drum 16 defining at least a portion of a laundrytreating chamber 18. The drum 16 can include a plurality of perforations20 such that liquid can flow between the tub 14 and the drum 16 throughthe perforations 20. A plurality of baffles 22 can be disposed on aninner surface of the drum 16 to lift the laundry load received in thetreating chamber 18 while the drum 16 rotates. It is also within thescope of the disclosure for the laundry holding system to comprise onlya tub with the tub defining the laundry treating chamber.

The laundry holding system can further include a door 24 which can bemovably mounted to the cabinet 12 to selectively close both the tub 14and the drum 16 at an access opening. A bellows 26 can couple the accessopening of the tub 14 with the cabinet 12, with the door 24 sealingagainst the bellows 26 when the door 24 closes the tub 14.Alternatively, a bellows may not be included, and the door 24 can sealdirectly against the tub 14 when closed.

The washing machine 10 can further include a suspension system 28 fordynamically suspending the laundry holding system within the structuralsupport system.

The washing machine 10 can further include a liquid supply system forsupplying water to the washing machine 10 for use in treating laundryduring a cycle of operation. The liquid supply system can include asource of water, such as a household or commercial water supply 40,which can include separate hot and cold water supplies, and variousconduits 42, 44, 50, 58, 60 and/or valves 46, 48, 54, 56 directing waterto areas of the washing machine 10. Water from the water supply 40 canbe supplied directly to the tub 14 via a spray nozzle 52 configured tospray a flow of water into the tub 14. Additional conduits and/or valves(not shown) can be provided for controlling the flow of hot and coldwater, respectively, to the spray nozzle 52.

The washing machine 10 can also be provided with a dispensing system fordispensing treating chemistry to the treating chamber 18 for use intreating the laundry according to a cycle of operation. The dispensingsystem can include a treating chemistry dispenser 62. The dispenser 62can be configured to dispense one or more treating chemistries directlyto the tub 14 or one or more treating chemistries mixed with water fromthe liquid supply system through an outlet conduit 64. The outletconduit 64 can include a dispensing nozzle 66 configured to dispense thetreating chemistry into the tub 14 in a desired pattern and under adesired amount of pressure. For example, the dispensing nozzle 66 can beconfigured to dispense a flow or stream of treating chemistry into thetub 14 by gravity, i.e. a non-pressurized stream. Additional conduitsand/or valves (not shown) can be provided for controlling the flow ofhot and cold water, respectively to the dispenser 62. Furthermore, whilethe dispensing system is shown as filling the tub 14 at the rear of themachine 10, alternatively the dispensing system can fill the tub 14 atthe front of the machine 10.

The washing machine 10 can also include a recirculation and drain systemfor recirculating liquid within the laundry holding system and drainingliquid from the washing machine 10. Liquid supplied to the tub 14typically enters a space between the tub 14 and the drum 16 and can flowby gravity to a sump 70 formed in part by a lower portion of the tub 14.The sump 70 can also be formed by a sump conduit 72 that can fluidlycouple the lower portion of the tub 14 to a pump 74. The pump 74 candirect liquid to a drain conduit 76, which can drain the liquid from thewashing machine 10, or to a recirculation conduit 78, which canterminate at a recirculation inlet 80. The recirculation inlet 80 candirect the liquid from the recirculation conduit 78 into the drum 16.The recirculation inlet 80 can introduce the liquid into the drum 16 inany suitable manner, such as by spraying, dripping, or providing asteady flow of liquid. In this manner, liquid provided to the tub 14,with or without treating chemistry can be recirculated into the treatingchamber 18 for treating the laundry within.

The liquid supply and/or recirculation and drain system can optionallybe provided with a heating system which can include one or more devicesfor heating laundry or liquid supplied to the tub 14, such as a steamgenerator 82 (FIG. 2) and/or a sump heater 84. Alternatively, the sumpheater 84 can be used to generate steam in place of or in addition tothe steam generator 82. In addition or alternatively to generatingsteam, the steam generator 82 and/or sump heater 84 can be used to heatthe laundry and/or liquid within the tub 14 as part of a cycle ofoperation.

Additionally, the liquid supply and recirculation and drain system candiffer from the configuration shown in FIG. 1, such as by inclusion ofother valves, conduits, treating chemistry dispensers, sensors, such aswater level sensors and temperature sensors, and the like, to controlthe flow of liquid through the washing machine 10 and for theintroduction of more than one type of treating chemistry.

The washing machine 10 also includes a drive system for rotating thedrum 16 within the tub 14. The drive system can include a motor 88,which can be directly coupled with the rotatable drum 16 through a driveshaft 90 at or about the rear cover to rotate the drum 16 about arotational axis during a cycle of operation. The motor 88 can be abrushless permanent magnet (BPM) motor having a stator 92 and a rotor94. Alternately, the motor 88 can be coupled to the drum 16 through abelt and a drive shaft to rotate the drum 16, as is known in the art.Other motors, such as an induction motor or a permanent split capacitor(PSC) motor, can also be used. The motor 88 can rotate the drum 16 atvarious speeds in either rotational direction.

The washing machine 10 also includes a control system for controllingthe operation of the washing machine 10 to implement one or more cyclesof operation. The control system can include a controller 96 locatedwithin the cabinet 12 and a user interface 98 that is operably coupledwith the controller 96. The user interface 98 can include one or moreknobs, dials, switches, displays, touch screens and the like forcommunicating with the user, such as to receive input and provideoutput. The user can enter different types of information including,without limitation, cycle selection and cycle parameters, such as cycleoptions.

The controller 96 can include the machine controller and any additionalcontrollers provided for controlling any of the components of thewashing machine 10. For example, the controller 96 can include themachine controller and a motor controller. Many known types ofcontrollers can be used for the controller 96. The specific type ofcontroller is not germane to the invention. It is contemplated that thecontroller is a microprocessor-based controller that implements controlsoftware and sends/receives one or more electrical signals to/from eachof the various working components to effect the control software. As anexample, proportional control (P), proportional integral control (PI),and proportional derivative control (PD), or a combination thereof, aproportional integral derivative control (PID control), can be used tocontrol the various components.

As illustrated in FIG. 2, the controller 96 can be provided with amemory 100 and a central processing unit (CPU) 102. The memory 100 canbe used for storing the control software that is executed by the CPU 102in completing a cycle of operation using the washing machine 10 and anyadditional software. Examples, without limitation, of cycles ofoperation include: wash, heavy duty wash, delicate wash, quick wash,pre-wash, refresh, rinse only, and timed wash. The memory 100 can alsobe used to store information, such as a database or table, and to storedata received from one or more components of the washing machine 10 thatcan be communicably coupled with the controller 96. The database ortable can be used to store the various operating parameters for the oneor more cycles of operation, including factory default values for theoperating parameters and any adjustments to them by the control systemor by user input.

The controller 96 can be operably coupled with one or more components ofthe washing machine 10 for communicating with and controlling theoperation of the component to complete a cycle of operation. Forexample, the controller 96 can be operably coupled with the motor 88,the pump 74, the dispenser 62, the steam generator 82, the sump heater84, or the like, to control the operation of these and other componentsto implement one or more of the cycles of operation. Other componentscan include, but are not limited to, valves 46, 48, 54, 56.

The controller 96 can also be coupled with one or more sensors 104provided in one or more of the systems of the washing machine 10 toreceive input from the sensors, which are known in the art and not shownfor simplicity. Non-limiting examples of sensors 104 that can becommunicably coupled with the controller 96 include: a treating chambertemperature sensor, a moisture sensor, a weight sensor, a chemicalsensor, a position sensor, or a motor torque sensor, which can be usedto determine a variety of system and laundry characteristics, such aslaundry load inertia or mass.

During operation of the washing machine, aspects of the disclosure orcontroller 96 can operably control, enable, or otherwise causes themotor 88 to rotate the drum 16 at various points, cycle, modes ofoperations, or the like. For example, during a spin or extraction phaseof a cycle of operation, the drum 16 is accelerated to a high number ofrotations per minute (RPM) to remove liquid from the clothes load. Thevoltage required to drive the motor 88 can periodically exceed a normal120 VAC input supplied from a North American power grid. Suchintermittent demands can request, desire, or otherwise demand, forexample, 240 VAC.

FIG. 3 shows a diagram of a circuit 201, such as a voltage doublingcircuit, that outputs DC voltage to a variable frequency drive (VFD)200, which further operates the motor 88. In one non-limiting example,the circuit 201 or VFD 200 can be one non-limiting example of an aspectconfigured to operably control, enable, or otherwise cause the motor 88to operate. In another non-limiting example, the circuit 201 can outputa DC voltage that is greater than an AC input voltage supplied to thecircuit. Starting from the left of FIG. 3, the circuit 201 includes a120 VAC input voltage source 203 across a line in 202 and a neutral line204. The controller can control a contactor, connector, switch, relay,or the like, to enable current to flow to the circuit 201. When the 120VAC input voltage source 203 is turned ON, current is allowed to flowthrough a Fuse 206 coupled to the line in 202.

The circuit 201 includes a power module 207 with two diodes 208 and 210and two banks of capacitors, an upper capacitor bank 220, and a lowerbank 230, directly connected to the input of the VFD 200. While “upper”and “lower” capacitive banks 220, 230 are described for ease ofunderstanding, any first capacitor set or bank, and second capacitor setor bank can be included in aspects of the disclosure, regardless orrelative positioning to each other. Diodes 208 and 210 can be, but arenot limited to, a standard diode array capable of an average rectifiedcurrent of 30-120 A per diode.

Each capacitor in the upper and lower capacitor banks 220, 230 can be,but is not limited to, a 200 volt capacitor with a capacitance of 1 mF.The upper and lower capacitor banks 220, 230 can be arranged such thatthe upper capacitor bank 220 (which can include a set of parallelcapacitors) is in series with the lower capacitor bank 230 (which caninclude a different set of parallel capacitors), wherein the distalterminal ends of the respective upper and lower capacitor banks 220, 230are conductively connected with the line in 202, and the seriesconnection between the upper and lower capacitor banks 220, 230 isconductively connected with the neutral line 204. In this example, thedistal terminal ends of the respective upper and lower capacitor banks220, 230 are further connected with the input of the VFD 200.

The circuit 201 can include a voltage doubling circuit. The power module207 including diodes 208 and 210 in combination with the upper and lowercapacitor banks 220, 230 at least partially to form a full wave voltagedoubler. Standard voltage readings; such as the example of the 120 VACinput voltage source 203, are representative of a root mean square (RMS)voltage value. In one non-limiting example, the peak voltage of the 120VAC input voltage source 203 is approximately 170 VAC. The circuit 201,containing the full wave voltage doubling components rectifies anddoubles the 170 VAC from the 120 VAC input voltage source 203 to andoutput voltage to the VFD 200 of approximately, or up to, 340 VDC.

Control features are included in the circuit 201 to ensure correctoperation with the contactor and VFD 200. Control features can include,but are not limited to, a current-limiting surge suppressor 240, ametal-oxide-semiconductor field-effect transistor (MOSFET) bypass 250,and a current drain 270.

The current-limiting surge suppressor 240 can be any current-limitingdevice. A non-limiting example of the current-limiting surge suppressor240 can include surge resistors 241 and 242 in series, and arranged inparallel to the MOSFET bypass 250. The surge resistors 241 and 242 caninclude, but are not limited to, thermistors selected to protect thecircuit from sudden increases in current that might be disruptive tooperation. The MOSFET bypass 250 can include, but is not limited tofield-effect transistors (FETs) 252 and 254 arranged in series, and canbe, but are not limited to, n-channel MOSFETS.

The current-limiting surge suppression, by the surge suppressor 240,occurs during periods of time wherein current flows through the surgeresistors 241 and 242, operably or effectively charging the upper andlower capacitor banks 220, 230. In one non-limiting example, the periodof time can include during an initial period of charging the upper andlower capacitor banks 220, 230. Once the upper and lower capacitor banks220, 230 are charged to a minimum predetermined voltage value, a MOSFETbypass 250 can be enabled to operably or effectively bypass the surgeresistors 241 and 242. The predetermined voltage value corresponds tothe voltage threshold of a Zener diode 294.

The MOSFET bypass 250 is triggered by the Zener diode 294. The Zenerdiode 294 passes current provided by the line in 202 source once thestored energy in the capacitor bank 220 results in a voltage that causesreverse current flow (specified breakdown level) through the Zener diode294. That current charges capacitors 256 and 258 (associated with,respectively, FETs 252 and 254). Zener diodes have a highly doped p-njunction that prevents the flow of current from the cathode to anodeuntil a voltage threshold (also known as the Zener Voltage) is reached.Once the voltage threshold is reached, current flows from the negativeto the positive terminal. In one non-limiting example, the Zener diode294 can have, but is not limited to, a voltage threshold of 120 VDC,therefore capacitors 256 and 258 do not begin charging until the uppercapacitor bank 220, reach a minimum voltage charge of 120 VDC. Thus, theperiod of initial charge of the upper and lower capacitor banks 220,230, for example, up to 120 VDC (each), will also coincide with ordefine the initial period of time that the surge suppressor 240 operablyprovides current-limiting surge suppression, as described herein.

The capacitors 256 and 258 can be, but are not limited to, 50 voltcapacitors with a capacitance of 10 microFarads. Once capacitors 256 and258 are charged, proper voltage differences will completely open theMOSFET bypass 250. The MOSFET bypass 250 includes FETs 252 and 254. FETs252 and 254 can be, but are not limited to, a 200 volt MOSFET capable of130 Amps with typical resistance of 8.0 milliOhms (max. resistance 9.7milliOhms). Resistors 296 and 298, in respective series with thecapacitors 256 and 258, and parallel resistors 260 and 262 can beselected, configured, adapted, or the like, based on considerationsincluding, but not limited to, regulating or defining the timing andactivation of FETs 252 and 254 to effectively operate current-limitingsurge suppression or to effectively bypass the current-limiting surgesuppression.

Once activated, the MOSFET bypass 250 performs as an extremely efficientswitch that quickly bypasses the surge resistors 241 and 242. The gatevoltage of FETs 252 and 254 are protected by Zener diodes 300 and 302,arranged in parallel, respectively, with capacitors 256 and 258. Zenerdiodes 300 and 302 can have, but are not limited to, a voltage threshold(“Reverse Breakdown”) of 27V.

In one non-limiting example, the upper and lower capacitor banks 220,230 can be discharged based on loosing input power line in 202 and priorto the next contactor closure. When the 120 VAC input voltage source 203and current to the circuit 201 are not provided, the FETs 252 and 254gate signals are reset (to 0V or near 0V); shutting them off andblocking the flow of current though MOSFET bypass 250. This effectivelyor operably re-enables the current-limiting surge suppressor 240. Thisdischarge results in all components in the circuit ready to start up inthe same condition each time.

The current drain 270 control feature can include, but is not limitedto, optocouplers 271 and 272, Zener diodes 274 and 276, and FET 278.Optocouplers transmit an electrical signal using a light source that isproportional to the electrical signal. The light source is detected by aphoto-sensitive material which transmits the signal based on theintensity of the light. Optocouplers can connect two separate circuits,while providing electrical isolation to further protect circuitcomponents.

The current drain 270 is connected to the line in 202 and neutral line204 by way of a voltage regulator 280 in series with another optocoupler282. When the contactor connects the circuit 201 to the 120 VAC inputvoltage source 203 current flows through a diode 290 to charge acapacitor 292 across the input of the voltage regulator 280. Diode 290and capacitor 292 are selected to specifically support the function ofthe voltage regulator 280. The voltage regulator 280 can be, but is notlimited to, a linear regulator system that can regulate, change, orotherwise convert a first power received at the input to a second,different power, provided to the output, in order to provide a constantoutput voltage. In a non-limiting example, the voltage regulator can beselected, configured, or operated to supply a non-zero voltage andcurrent, such as a 5 V output at 5 milliAmps. While the voltageregulator 280 is powered, voltage is applied across a capacitor 281 inparallel to the voltage regulator 280. Current flows through a resistor284. The capacitor 281 and the resistor 284 regulate the voltage andcurrent to an optocoupler 282. The optocoupler 282 then drains thevoltage to the “gate” control of FET 278 such that FET 278 is closed;closing the current drain 270.

The current drain 270 control feature drains the charge of the upper andlower capacitor banks 220, 230. When the contactor is off, the voltageregulator 280 also switches off. Once the voltage regulator 280 is off,the FET 278 receives voltage (positive from the neutral line 204 andnegative from the lower capacitor bank 230) which activates it. The FET278, when active, supplies current to a series of optocouplers 271 and272. Resistor 304, in series with optocoupler 271, can be selected toensure the current is at the correct input value according to therequirements of the optocoupler 271. Current from optocouplers 271 and272 deactivates FETs 252 and 254 of the MOSFET bypass 250 to close,resetting the current-limiting surge suppressor 240 as the only path toprovide surge suppression in the next operation cycle.

When the FET 278 is activated, it also allows the circuit 201 to drain.Current flowing to the drain is dissipated using a high power resistor306. The resistor 306 can balance discharging at a reasonable rate (fastas possible) and the power required to pass high current to discharge atthat rate. This allows the circuit 201 to drain charge stored by theupper or lower capacitor banks 220, 230. Stored charge can drain fromthe positive of the upper capacitor bank 220 to the negative of thelower capacitor bank 230. During this process, resistor 308 prevents toomuch current from overwhelming the Zener diode 274 as the circuitdischarges. The Zener diode 274 limits the voltage to the FET 278. Acapacitor 310 can be optional and helps to hold the Zener diode 274 openlonger by providing appropriate voltage, so that the upper and lowercapacitor banks 220, 230 can discharge stored charge to zero ornear-zero voltage. In one aspect of the present disclosure, after thepower is removed (e.g. by opening the contactor), the voltage can reacha “safe” level (e.g. less than 24 VDC) in about 32 seconds.

The circuit 201 further resets as the voltage drops below 80V, FET 278in the current drain 270 is permitted to turn on.

FIG. 4 illustrates a flow chart representative of current flow 400during operation of the circuit 201. First, service power, such as 120VAC, is supplied by the 120 input voltage source 203, at 402. At 404,the circuit 201 can operate in distinct fashions, depending on whetherthe service power is applied to the circuit 201, such as if thecontactor is open or closed. If service power is not applied to thecircuit (“NO” branch of 404), the current drain 270 control feature isoperated to effectively enable the discharging or draining of thecapacitor banks 220, 230, as described herein, at 420. If service poweris applied to the circuit 201 (“YES” branch of 404, current flowsthrough the fuse 406. Current then flows simultaneously to the voltageregulator 280, the current-limiting surge suppressor 240, and the powermodule 207, at 408. During this period of time, the upper and lowercapacitor banks 220, 230 of the power module 207 begin to charge, asdescribed herein.

The circuit 201 continues to charge the upper and lower capacitor banks220, 230 via the current-limiting surge suppressor 240. The positivehalf wave of the 120 VAC input voltage source 203 (also known as an ACpower source) can charge the upper capacitor bank 220 while the negativehalf wave of the 120 VAC input voltage source 203 can charge the lowercapacitor bank 230. At 410, if the upper and lower capacitor banks 220,230 are not charged to 70% of their capacitance (“NO” branch of 410),the circuit 201 will continue to charge the upper and lower capacitorbanks 220, 230 of the power module 207 with the current-limiting surgesuppressor 240, as described herein. In this non-limiting example, thecurrent-limiting surge suppressor 240 can be configured or adapted toprovide current limiting protection up to or beyond 70% of the uppercapacitor bank 220 capacitance. Once the upper capacitor bank 220reaches a charge of 70% of their capacitance (“YES” branch of 410),current flows through Zener diode 294, charging capacitors 256 and 258which enables the MOSFET bypass 250, in 412. The MOSFET bypass 250performs as an extremely efficient switch and allows current to flowthrough the power module 207 and complete charging the upper and lowercapacitor banks 220, 230 with less input resistance, compared with whenthe current-limiting surge suppressor 240 is enabled.

In 414, the upper bank of capacitors 220 contributes to an increase inthe positive portion of the original AC signal from the 120 VAC inputvoltage source 203. A half wave cycle later (that can be, but is notlimited to 8 ms) in the AC signal, the lower bank of capacitors 230triggers an increase in the negative portion of the original 120 VACinput voltage source 203. Combining the 120 VAC input voltage source 203and capacitor voltage from the upper and lower capacitor banks 220, 230allows for a DC output voltage greater than 120V to the VFD 200. Theupper and lower capacitor banks 220, 230 can charge up to approximately340 VDC; double the 170 VAC peak voltage of the 120 VAC input voltagesource 203. The VFD 200 usually changes VAC to VDC using diodes, so a DCrather than AC input provides no issue for the VFD 200. In anon-limiting example, a minimum voltage required for the VFD 200 tooperate can be 240 VDC. Additionally or alternatively, the current fromthe circuit 201 can directly connect to DC input terminals of the VFD200; bypassing the diodes and the power that would normally be used tochange VAC to VDC.

In 416, current from the VFD 200, can be utilized to operate the motor88. The upper and lower capacitor banks 220, 230 help maintain the DCoutput voltage to the VFD 200 at or greater than 240 VDC for a longenough period of time to enable accelerating the drum to a high speed,such as during a spin or water extraction cycle of operation. In onenon-limiting example, the high energy storage of the upper and lowercapacitor banks 220, 230 are needed to help maintain the DC outputvoltage to the VFD 200 for a few seconds. In another non-limitingexample, the upper and lower capacitor banks 220, 230 can only need tohelp maintain the DC output voltage to the VFD 200 while the motor 88 isoperating with the higher power draw operation, compared with othercycles or sub-cycles of operation. As used herein, a “higher power drawoperation” can include a power output draw from the VFD 200 between100%-200%, for example, when using a 7 Amp VFD. In another non-limitingexample when using a higher power VFD, for example a 10 Amp VFD, a“higher power draw operation” can include a power output draw from theVFD 200 of less than 100%. After the highest power draw, greatestacceleration, or combination thereof is over, the voltage doublingoperation of the circuit 201 can operate to recharge the upper and lowercapacitor banks 220, 230 to maintain a normal DC voltage level up toabout 340 VDC.

It will be understood that 404 occurs contemporaneously with 406-416. Ifat any time the service power applied to the circuit 201 ceases, thecurrent drain 270 can open to discharge the capacitor banks 220, 230, at420. As explained herein, when the contactor is off, the voltageregulator 280 also switches off, allowing or enabling the current drain270 to drain in 412.

FIG. 5 demonstrates a voltage verses time graph 500 for aspects of thecircuit 201. Lines 504, 510, 520 are illustrative of the voltage acrossthe upper and lower capacitor bank 220, 230 of circuit 201. Lines 508,514, 518 are illustrative to the voltage across capacitors 256 and 258.

At time (t0) 502 the 120 VAC input voltage source 203 is supplied tocircuit 201 via the contactor. From the time (t0) 502 to a time (t1)506, the line 504 illustrates the increasing voltage of the upper andlower capacitor banks 220, 230 as current flows through the fuse 206,the power module 207, and the current-limiting surge suppressor 240 toprovide increasing charge. The current drain 270 remains closed by thevoltage regulator 280 that shorts the FET 278. At the time (t1) 506 thecharge on the upper and lower capacitor banks 220, 230 reachesapproximately 70% of the total capacitance. At this voltage, currentbegins to flow through the Zener diode 294. Between the time (t1) 506and a time (t2) 512, current flowing through the Zener diode 294 chargesthe capacitors 256 and 258, as shown by line 508. As the capacitors 256and 258 charge, the input resistance begins to drop as current begins toflow through the MOSFET bypass 250. This enables the upper and lowercapacitor banks 220, 230 to continue to charge quickly and completely asshown by line 510 from the time (t1) 506 to the time (t2) 512.

Between the time (t2) 512 and a time (t3) 516, the capacitors 256 and258 continue to charge as shown by line 514. The MOSFET bypass 250completely bypasses the current-limiting surge suppressor 240 and theupper and lower capacitor banks 220, 230 are fully charged asillustrated by line 520. At the time (t3) 516 the capacitors 256 and 258are fully charged as shown by line 518.

To the extent not already described, the different features andstructures of the various aspects can be used in combination with eachother as desired. That one feature cannot be illustrated in all of theaspects is not meant to be construed that it cannot be, but is done forbrevity of description. Thus, the various features of the differentaspects can be mixed and matched as desired to form new aspects, whetheror not the new aspects are expressly described. Combinations orpermutations of features described herein are covered by thisdisclosure.

Benefits and advantages include, but are not limited to, an ability tosupply as much as 340 VDC to a VFD 200. While high output voltagedecreases during periods of high current draw, the rate at which thecircuit can recharge increases as the output voltage decreases. Thisallows for a wide variety of aspects of the invention to sustainacceptably high voltage output to a variety of applications involvingVFDs.

This written description uses examples to disclose aspects of thedisclosure, including the best mode, and also to enable any personskilled in the art to practice aspects of the disclosure, includingmaking and using any devices or systems and performing any incorporatedmethods. While the invention has been specifically described inconnection with certain specific aspects thereof, it is to be understoodthat this is by way of illustration and not of limitation. Reasonablevariation and modification are possible within the scope of the forgoingdisclosure and drawings without departing from the spirit of theinvention which is defined in the appended claims. For example, a relaycould be used instead of the MOSFET bypass. Another example could be theuse of certain transistors or relays instead of optocouplers. Aspects ofthis invention could be applied to any VFD device that requires highvoltage continuously as well as high power (for example, but not limitedto, 750 Watts or more) for a finite length of time during use.

What is claimed is:
 1. A home appliance configured to perform a cycle ofoperation, comprising: a motor; and a voltage doubling circuit, furthercomprising: a power input configured to receive a voltage supply from apower source; at least one capacitor bank connected with the powerinput; a current-limiting surge suppressor positioned between the powerinput and the at least one capacitor bank; a voltage drain configured todissipate a charge of the at least one capacitor bank; and a variablefrequency drive (VFD) configured to cause the motor to operate, andoperable when supplied with a voltage greater than the voltage supplyfrom the power source.
 2. The home appliance of claim 1 wherein thevoltage supply from the power source is alternating current (AC) and theVFD is operable when supplied with voltage that is direct current (DC).3. The home appliance of claim 2 wherein the at least one capacitor bankincludes a first capacitor bank configured to be charged by a positivehalf wave of the AC power source and a second capacitor bank configuredto be charged by a negative half wave of the AC power source.
 4. Thehome appliance of claim 3 wherein the first capacitor bank is in serieswith the second capacitor bank.
 5. The home appliance of claim 4 whereinthe VFD is operable when supplied with a voltage that is at least twicethe voltage of the voltage supply.
 6. The home appliance of claim 1wherein the current-limiting surge suppressor includes acurrent-limiting path and a parallel bypass path.
 7. The home applianceof claim 6 wherein the current-limiting path is enabled and the bypasspath is disabled until the at least one capacitor bank is charged toapproximately seventy percent of a peak voltage of the voltage supply.8. The home appliance of claim 6 wherein the bypass path has lessresistance compared with the current-limiting path.
 9. The homeappliance of claim 1 wherein the at least one capacitor bank is at leastpartially discharged during high power draw portions of the cycle ofoperation.
 10. The home appliance of claim 9 wherein the home applianceis a washing machine.
 11. The home appliance of claim 10 wherein thehigh power draw portion of the cycle of operation includes operating themotor to accelerate a drum within a tub.
 12. The home appliance of claim11 wherein the high power draw portion of the cycle of operationincludes at least one of a spin cycle or a extraction phase of the cycleof operation.
 13. The home appliance of claim 1 wherein the voltagedrain is configured to open in response to a ceasing of the voltagesupply from the power source.
 14. A home appliance configured to performa cycle of operation, comprising: a motor; and a voltage doublingcircuit, further comprising: a power input configured to receive avoltage supply from a power source; at least one capacitor bankconnected with the power input; a current-limiting surge suppressorpositioned between the power input and the at least one capacitor bankthat includes a current-limiting path and a parallel bypass path whereinthe current-limiting path is enabled and the bypass path is disableduntil the at least one capacitor bank is charged to approximatelyseventy percent of a peak voltage of the voltage supply; and a variablefrequency drive (VFD) configured to cause the motor to operate, andoperable when supplied with a voltage greater than the voltage supplyfrom the power source.
 15. The home appliance of claim 14 furthercomprising a voltage drain configured to dissipate a charge of the atleast one capacitor bank.
 16. The home appliance of claim 14 wherein theVFD is operable when supplied with a voltage that is at least twice thevoltage of the voltage supply.
 17. The home appliance of claim 14wherein the at least one capacitor bank is at least partially dischargedduring high power draw portions of the cycle of operation.
 18. A methodof operating a voltage doubling circuit for a laundry treating applianceconfigured to perform a cycle of operation, the method comprising:receiving, at the voltage doubling circuit, a voltage supply from apower source; charging at least one capacitor bank through acurrent-limiting surge suppressor defining a current-limiting pathconnected with the voltage supply; upon charging the at least onecapacitor bank to approximately seventy percent of a peak voltage of thevoltage supply, charging the at least one capacitor bank through abypass path configured to bypass the current-limiting path of thecurrent-limiting surge suppressor; and at least partially dischargingthe at least one capacitor bank to supply a voltage greater than thevoltage supply to a variable frequency drive (VFD) operable to cause amotor to operate during a high power draw portion of the cycle ofoperation, wherein the high power draw portion of the cycle of operationincludes causing the motor to accelerate.
 19. The method of claim 18wherein the laundry treating appliance is a washing machine, wherein thehigh power draw portion of the cycle of operation is at least one of anacceleration phase, a spin phase, or an extraction phase of a cycle ofoperation.
 20. The method of claim 18, further comprising recharging theat least one capacitor bank through at least one of the current-limitingpath or the bypass path after the at least partially discharging, basedon the stored charge of the at least one capacitor bank.